The present invention relates to a vane motor used in conjunction with a combustion member where fuel burning occurs externally to the motor. The association of such motor with the external combustion member basically constitutes the external combustion engine. Such association is described and discussed in detail in my U.S. Pat. No. 4,399,654 dated Aug. 23, 1983, where a slidable vane motor and variations thereof are utilized: (1) for compressing air, (2) for expanding combusted gas and extracting energy therefrom, and (3) for producing energy delivered by an externally located power shaft.
The vanes of such motor must slide in and out of guiding slots as the motor rotates. The vanes are solicited to tilt by the pressure difference applied on their surfaces. The resulting torques must be reacted by the guiding surfaces of their corresponding slots. Friction between the cooperating sliding surfaces of both vanes and slots is conducive to wear. Lubrication of the sliding surfaces is difficult and results in the production of undesirable carbonaceous deposited by-products. The operating temperatures of the parts are high and cooling is not practical. However, the simplicity of a vane motor is appealing and efforts to develop vane motors which require neither lubrication nor cooling is considered very worthwhile in the case of the present application.
When fuel combustion is performed externally, the motor parts and especially the vanes are not subjected to the rapidly varying pressures, or even shocks, which combustion often causes. In addition, the magnitude of temperature gradients in moving parts is also lessened. Newer materials such as ceramics and densified carbon/graphite composites are being developed. They offer the advantages of high temperature resistance combined with low thermal expansion. Thus, they allow the elimination of cooling. The next step is to attempt to eliminate friction, thereby lubriction and sliding surface wear.
In view of this background, it is an object of the present invention to provide a new and improved vane motor for an external combustion engine which combines construction features that enables the motor to operate without cooling and lubrication.
It is another object of the present invention to prevent moving motor parts from contacting non-moving parts during the engine operation so as to prevent part wear.
It is another object of the present invention to provide air cushions between moving and fixed parts of the motor.
It is another object of the present invention to cause the air cushions to self-regulate the pressure of the air inside the cushions so as to create automatic feedback between moving part off-centering and the restoring actions of the air cushions.
Finally it is still another object of the present invention to provide a new and improved slidable vane motor for use with an external combustion member so as to minimize the magnitude of the mechanical and thermal loads imposed by the combustion process on the moving parts of the slidable vane motor.